The terms empathogen and entactogen are used to describe a class of psychoactive drugs that produce distinctive emotional and social effects similar to those of MDMA (ecstasy). Putative members of this class include 2C-B, 2C-I(at 2-14mg), MDMA, MDA, MDEA, MBDB, 6-APB and mephedrone among others. The chemical structure of many entactogens contains a substituted amphetamine core, and most belong to the phenethylamine class of psychoactive drugs, although several (AET and AMT) are tryptamines. When referring to MDMA and its counterparts, the term 'MDxx' is often used with the exception of MDPV. Entactogens are sometimes incorrectly referred to as major hallucinogens or stimulants, which is untrue although many entactogens exhibit psychedelic and/or stimulant properties as well.